CN111051606B

CN111051606B - Artificial leather having excellent surface appearance and method for manufacturing the same

Info

Publication number: CN111051606B
Application number: CN201880057137.7A
Authority: CN
Inventors: 闵喆熙; 郑龙培; 李寅赫
Original assignee: LG Hausys Ltd
Current assignee: LX Hausys Ltd
Priority date: 2017-09-14
Filing date: 2018-09-11
Publication date: 2023-06-13
Anticipated expiration: 2038-09-11
Also published as: KR20190030597A; KR102080403B1; US20200232157A1; CN111051606A

Abstract

The present invention relates to an artificial leather, and more particularly, to an artificial leather which is used as an automobile seat cover and has an excellent surface appearance by being subjected to a surface treatment before embossing forming for imparting a texture and a cushioning effect to a natural leather, thereby providing a surface treatment layer having a uniform thickness, and a method for manufacturing the same.

Description

Artificial leather having excellent surface appearance and method for manufacturing the same

Technical Field

Background

In general, the interior of an automobile is regarded as a second living space, and recently, a functional seat is attracting attention for comfortable and pleasant driving in such an interior space of an automobile.

As a material for automobile seats, artificial leather such as polyvinyl chloride and polyurethane is cheaper than natural leather and satisfies the touch and functionality of natural leather, and development has been conducted.

Specifically, the conventional artificial leather is composed of a laminated structure including a backing layer, a foaming layer, a surface layer, and a surface treatment layer from bottom to top.

In particular, as in korean patent laid-open publication No. 10-1361535 (publication day: 13 of 2014, 02), embossments are formed by using a roll type in which embossments are transferred between embossing rolls so as to impart a texture and a cushioning sensation to the upper portion of the surface layer of natural leather.

Then, a surface treatment agent is coated on the upper portion of the surface layer on which the embossments are formed to form a surface treatment layer, at this time, there is a problem in that the amount of the surface treatment agent coated on the valleys and peaks of the embossments may vary considerably, resulting in uneven thickness of the surface treatment layer, and the valley or peak portions may look brighter than other regions due to the difference in gloss of the valleys and peaks, and the appearance may be uneven.

Prior art literature

Patent literature

( Patent document 0001) KR 10-1361535B (bulletin day: 2014, 02, 13 )

Disclosure of Invention

Technical problem

The present invention aims to provide artificial leather having an excellent surface appearance.

Another object of the present invention is to provide a method for manufacturing artificial leather capable of performing surface treatment before embossing.

Technical proposal

The present invention provides an artificial leather, wherein the ratio of the thickness of a surface treatment layer formed on embossed peaks to the thickness of a surface treatment layer formed on embossed valleys is 0.7-1.

In addition, the present invention provides an artificial leather manufacturing method for manufacturing the artificial leather, comprising:

a backing layer coating step of coating a coating solution on one surface of a backing layer, wherein the backing layer is woven fabric or non-woven fabric;

forming a prefabricated foaming layer or a foaming layer and a surface layer, and respectively forming the prefabricated foaming layer or the foaming layer and the surface layer;

a backing layer laminating step of laminating the backing layer with a surface coated on the bottom surface of the prefabricated foaming layer or the foaming layer;

a surface layer laminating step of laminating the surface layer on top of a pre-formed foam layer or a foam layer formed with the backing layer;

a surface treatment layer forming step of applying an aqueous surface treatment agent to an upper portion of the surface layer to form a surface treatment layer;

an infrared irradiation step of irradiating an upper portion of the surface treatment layer with infrared rays;

and an embossing step of forming embossing by adsorption on the upper parts of the surface layer and the surface treatment layer heated by irradiation of the infrared rays by vacuum.

Advantageous effects

In the artificial leather of the present invention, the surface treatment layer formed on the embossed valleys and peaks has a uniform thickness and thus has an excellent surface appearance.

In addition, the artificial leather of the present invention has a texture and soft touch similar to those of natural leather.

In addition, the artificial leather of the present invention can prevent the foaming unit constituting the foaming layer from being distorted or broken, thereby achieving an effect of excellent cushioning feeling.

Drawings

Fig. 1 is a side sectional view showing a laminated structure of the artificial leather of the present invention.

Fig. 2 is a flowchart showing the artificial leather manufacturing process of the present invention.

Fig. 3 is a photograph showing the surface (embossing) of the artificial leather of the present invention.

Fig. 4 is a photograph showing a surface (embossing) of a conventional artificial leather coated with a surface treating agent after embossing by roll forming.

Fig. 5 is a diagram schematically showing a method of measuring a gloss difference of a surface appearance of an artificial leather.

Reference numerals

10: artificial leather 11: backing layer

13a: preformed

foam layer

13b, 13b': foaming layer

15: surface layer 17: surface treatment layer

19: embossing 19a: embossed cereal

19b: peaks of embossment

Detailed Description

The constitution and operation of the preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

In the case where reference numerals are added to the respective components, the same reference numerals are used as much as possible even if the components are shown in different drawings.

Fig. 1 is a side sectional view showing a laminated structure of the artificial leather of the present invention, the artificial leather 10 of the present invention includes a backing layer 11,

foaming layers

13b, 13b', a surface layer 15, and a surface treatment layer 17 from bottom to top, and may further include embossments 19 formed on the upper portions of the surface layer 15 and the surface treatment layer 17.

Specifically, in the artificial leather 10 of the present invention, the ratio of the thickness of the surface treatment layer formed on the peaks (crest) 19b of the embossed patterns 19 to the thickness of the surface treatment layer formed on the valleys (valley) 19a of the embossed patterns 19 (i.e., the thickness of the surface treatment layer formed on the peaks/the thickness of the surface treatment layer formed on the valleys) may be 0.7 to 1 or 0.8 to 1, and when the ranges are within the above ranges, the difference in gloss of the surface treatment layer formed on the valleys and the peaks is small, and the surface does not look uneven, so that it is possible to provide an artificial leather excellent in appearance.

In the present invention, the embossed valleys (valley) represent the lowest positions, and the embossed peaks (crest) represent the highest positions (see fig. 3) as the protruding portions.

The ratio of the thickness of the surface treatment layer formed on the valleys 19a to the peaks 19b of the embossed patterns 19 may be calculated by measuring the thickness of the surface treatment layer using a high-magnification optical microscope after cutting the artificial leather 10 in the vertical direction, and by the thickness of the surface treatment layer formed on the peaks/the thickness of the surface treatment layer formed on the valleys.

In the artificial leather 10 of the present invention, the difference in thickness between the surface-treated layers formed on the valleys 19a and the peaks 19b of the embossed patterns 19 is less than 5 μm or less than 3 μm, and when the difference in gloss between the surface-treated layers formed on the valleys 19a and the peaks 19b is within the above range, the surface does not look uneven, and therefore an artificial leather excellent in appearance can be provided.

Specifically, in order to prevent damage to the surface treatment layer of the conventional artificial leather in which the embossing is formed by the roll embossing roll, the surface treatment agent is applied only after the embossing, and there is a problem in that the difference in thickness of the surface treatment layer formed between the valleys 19a and the peaks 19b of the embossing 19 is 5 μm or more, and the difference in gloss of the surface treatment layer formed between the valleys 19a and the peaks 19b is large, so that the appearance is poor. The artificial leather 10 of the present invention can be surface-treated before the embossing 19 is formed, and thus the thickness of the surface-treated layer formed on the valleys 19a and the peaks 19b of the embossing 19 is uniform, and thus an artificial leather excellent in appearance can be provided.

In this way, the area where the ratio of the thickness of the surface treatment layer formed on the valleys 19a and the peaks 19b of the embossed patterns 19 or the difference between the thicknesses satisfies the above range can occupy 80% or more or 90% or more of the entire surface of the artificial leather.

More specifically, as described above, in the artificial leather 10 of the present invention, the difference in thickness of the surface treatment layer formed between the valleys 19a and the peaks 19b of the embossments 19 is less than 5 μm, and thus, there is no gloss difference between the valleys 19a and the peaks 19b of the embossments 19.

The gloss difference is a difference in brightness induced by a difference in gloss between the valleys 19a and the peaks 19b of the embossed patterns 19 due to a difference in reflectance when the artificial leather sample is inclined at 30 ° to 60 ° with respect to the incident angle of light under light having a wavelength of 380 to 800nm and observed with the naked eye.

More specifically, a group of 10 evaluators was used to measure whether or not the artificial leather sample was visually inspected for the difference in gloss between the valleys 19a and the peaks 19b of the striae 19, and when the number of people who considered to have the difference in gloss was 5 or more, the difference in gloss was defined as X (poor appearance), and when the number of people considered to have the difference in gloss was less than 5, the difference in gloss was defined as no difference in gloss, and the difference was defined as o (excellent appearance).

The method of measuring the difference in gloss between the valleys 19a and the peaks 19b of the embossed patterns 19 in the artificial leather sample is to make the light (light source), the artificial leather sample and the eyes of the evaluator at right angles, and in this case, the artificial leather sample and the eyes of the evaluator are positioned in the same straight line.

Thereafter, the artificial leather sample was repeatedly inclined at 30 ° to 60 ° based on the incident angle of light, and as shown in fig. 3 and 4, based on the valley 19a portion of the embossed pattern 19, whether or not the difference in gloss was visible was measured (see fig. 5).

In addition, in measuring whether or not the gloss difference exists, the distance between the artificial leather sample and the eyes of the evaluator may be 30cm or less or 20cm. When it is larger than the above range, it is difficult to measure the difference in gloss between the valleys 19a and the peaks 19b of the embossed patterns 19, and only the increase in the overall gloss of the artificial leather sample can be sensed visually, and thus, it is possible to be within the above distance range.

Further, the artificial leather 10 of the present invention can be surface-treated before embossing, and thus, the surface-treated layer can be processed together with the embossing at the time of embossing, thereby forming roughness (Ra) in accordance with the shape of the embossing, however, the conventional artificial leather in which the embossing is formed by using the roll type embossing roller is coated with more surface-treating agent than peaks at the time of applying the surface-treating agent after embossing, and thus, the surface of the artificial leather becomes somewhat flat, and therefore, roughness (Ra) is lower than the artificial leather 10 of the present invention.

On the other hand, the microhardness of the artificial leather 10 of the present invention may be 45 to 59 or 50 to 57.

The microhardness is a local hardness of a minute sample having a thickness of about 0.5 to 1.5mm, and is a maximum value measured after a indenter (model: MD-1 CAPA) is brought into contact with the artificial leather at an indentation speed of 1mm/s in a peak hold mode by a microhardness meter (Asker Micro Durometer Co., ltd.), that is, when the load hold time of the indenter is 1 s.

Specifically, there are various methods for measuring Hardness, such as Shore Hardness (Hardness Shore, "HS"), duplex Rock, "HR", vickers Hardness (Hardness Vickers, "HV"), knoop Hardness (Hardness Knoop, "HK"), and microhardness. Among the above-mentioned various hardness measurement methods, shore hardness is generally used in measuring the hardness of artificial leather.

However, the Shore hardness is a method for measuring a specimen having a thickness of 5mm or more, and is not suitable for measuring the hardness of a minute specimen having a thickness of less than 5 mm.

The microhardness is a specimen having a thickness of less than 5mm, and may be, for example, the hardness of the above-mentioned minute specimen having a thickness of 0.5 to 1.5mm, and may be, for example, MD-1CAPA of Asker Micro Durometer, a microhardness meter for measuring microhardness.

When the microhardness is more than the above range, the feel is generally not soft, but when it is less than the above range, the mechanical properties such as abrasion resistance are reduced, and therefore, the microhardness in the above range can be provided to have soft and excellent cushioning feel.

Next, the method of manufacturing the artificial leather 10 is as follows.

Referring to fig. 2, the present invention relates to a method for manufacturing artificial leather, comprising:

a backing layer coating step S1, wherein a coating solution is coated on one surface of a backing layer, and the backing layer is woven fabric or non-woven fabric;

step S3, forming a prefabricated foaming layer or a foaming layer and a surface layer, and respectively forming the prefabricated foaming layer or the foaming layer and the surface layer;

a backing layer laminating step S5, wherein the backing layer with a coated surface is laminated on the bottom surface of the prefabricated foaming layer or the foaming layer;

a surface layer lamination step S7 of laminating the surface layer on top of a pre-formed foam layer or a foam layer on which the backing layer is formed;

a surface treatment layer forming step S9 of applying an aqueous surface treatment agent to an upper portion of the surface layer to form a surface treatment layer;

an infrared irradiation step S11 of irradiating an upper portion of the surface treatment layer with infrared rays;

and an embossing step S13, wherein embossing is formed by adsorption on the upper parts of the surface layer and the surface treatment layer heated by irradiation of the infrared rays by vacuum.

The steps will be specifically described below.

Backing layer coating step S1

In step S1, the coating solution is applied to one surface of the backing layer 11, thereby improving the peel strength between the backing layer 11 and the foam layers 13b and 13b' on the upper portion of the backing layer 11.

Specifically, in the embossing step S13 of the artificial leather of the present invention, since the embossing is formed by suction by vacuum, the semi-finished product is not compressed at a large pressure as in the embossing formed by the conventional roll embossing roll, and thus there is a possibility that the peeling strength between the backing layer 11 and the foaming layers 13b and 13b' is lowered. Therefore, the backing layer 11 of the present invention is gelled (gelled) by heat treatment at 120 to 150 ℃ after the coating solution is applied to one surface thereof to improve the peel strength from the foamed

layers

13b, 13 b'.

The coating solution may be an acrylic binder, a polyurethane binder or a polyvinyl chloride Plastisol (plasitisol). However, the acrylic adhesive becomes hard after drying, and there is a disadvantage in that the microhardness of the artificial leather increases, and the polyurethane adhesive is relatively expensive and increases material costs, so that a polyvinyl chloride plastisol which is inexpensive and does not increase the microhardness of the artificial leather after drying can be used.

The polyvinyl chloride plastisol may be formed by stirring 70 to 130 parts by weight of a plasticizer and 0.5 to 10 parts by weight of a curing agent at normal temperature with respect to 100 parts by weight of a polyvinyl chloride resin.

Specifically, the polyvinyl chloride resin may be a mixed resin composed of 60 to 90% by weight of a homopolymer of vinyl chloride and 10 to 40% by weight of a copolymer of vinyl chloride and vinyl acetate.

The vinyl chloride homopolymer is a Paste (Paste) polyvinyl chloride resin produced by emulsion polymerization, and accounts for 60 to 90 wt% or 65 to 85 wt% of the mixed resin. When the amount is less than the above range, the peel strength between the backing layer 11 and the foam layers 13b and 13b' is reduced, and when the amount is more than the above range, an odor is generated, which is not preferable, and therefore, the amount may be contained in the above range.

The copolymer of vinyl chloride and vinyl acetate is a resin capable of imparting excellent adhesion to the backing layer 11 formed of woven or non-woven fabric, and the content of vinyl acetate in the copolymer may be 1 to 15% by weight or 3 to 10% by weight. When the amount is less than the above range, the adhesive force is lowered, resulting in lowering of the peel strength of the backing layer 11 and the foam layer 13b, and when the amount is more than the above range, the hydrolyzability is lowered, and thus the above range may be included.

In addition, the copolymer of vinyl chloride and vinyl acetate may account for 10 to 40% by weight or 15 to 35% by weight of the mixed resin. When the amount is less than the above range, the peel strength between the backing layer 11 and the foam layer 13b is reduced, and when the amount is more than the above range, the mechanical properties such as heat resistance are reduced, and therefore, the amount may be contained in the above range.

The plasticizer contained in the coating solution can be more than one selected from phthalate plasticizers, terephthalate plasticizers, benzoate plasticizers, citrate plasticizers, phosphate plasticizers or adipate plasticizers.

In the present invention, a terephthalate plasticizer which is environmentally friendly and has excellent heat resistance can be preferably used. As the terephthalate plasticizer, for example, dioctyl terephthalate may be used, but is not limited thereto.

The plasticizer may be contained in an amount of 70 to 130 parts by weight or 80 to 120 parts by weight based on 100 parts by weight of the mixed resin. When the viscosity of the coating solution is less than the above range, the workability is improved, whereas when the viscosity is more than the above range, the adhesion is reduced due to the transfer phenomenon of the plasticizer, and thus the coating solution may be contained in the above range.

The curing agent contained in the coating solution may be a low-temperature curing type curing agent to improve energy efficiency and productivity, and a blocked isocyanate curing agent blocked with a blocking agent may be used for part or all of the isocyanate groups.

The blocking agent may be one or more selected from phenol (phenol), epsilon-caprolactam (epsilon-caprolactam), methyl ethyl ketoxime (methyl ethyl ketone oxime), 1,2-pyrazole (1, 2-pyrazole), diethyl malonate (diethyl maleate), diisopropylamine (diisopropylamine), triazole (triazole), imidazole (imidazole), and 3,5-dimethylpyrazole (3, 5-dimethylpyrazole).

The blocked isocyanate curing agent blocks isocyanate groups at normal temperature to prevent isocyanate groups (-NCO) from reacting with hydroxyl groups (-OH) or amino groups (-NH), and when reaching a prescribed temperature region, the blocking agent dissociates, and at the same time, -NCO group reactivity increases to effect curing reaction.

The dissociation temperature of the curing agent can be above 100 ℃ or 110-130 ℃.

The curing agent may be contained in an amount of 0.5 to 10 parts by weight or 1 to 5 parts by weight based on 100 parts by weight of the mixed resin. When the amount is less than the above range, the peel strength between the backing layer 11 and the foam layers 13b and 13b' is reduced due to the reduced crosslinking degree, and when the amount is more than the above range, the curing agent which does not participate in the reaction remains and becomes impurities, and the usability is reduced, so that the use can be made of the above range.

The coating solution may optionally further contain one or more other additives selected from the group consisting of stabilizers, fillers, pigments, viscosity reducers, and dispersants, as required, and the content thereof is not limited as long as the physical properties of the coating solution are not affected.

The viscosity of the coating solution is measured as Cai Enbei (Zahn cup, #3 cup) and may be 80 to 140 seconds or 100 to 120 seconds at 25 ℃. When the viscosity is within the above range, the coating solution may flow down to lower the coating efficiency, and when the viscosity is greater than the above range, the coating solution may solidify at the time of coating to make it difficult to impregnate into the backing layer 11 composed of woven or nonwoven fabric, and when the viscosity is within the above range, stable processability can be ensured.

The backing layer 11 coated with the coating solution can assist mechanical properties and function to maintain the morphology of artificial leather, resist wrinkles, etc., and may be a flexible polymer such as woven fabric, nonwoven fabric, woven fabric, flat woven fabric, release fabric, etc., based on various composites of cotton, rayon, silk, polyolefin (e.g., polyethylene, polypropylene, etc.), nylon, polyester, polyurethane, etc., and may optionally further include natural fibers and/or synthetic fibers.

Preferably, the backing layer 11 may be a woven or nonwoven fabric comprising cotton or rayon and polyester in a weight ratio of 30 to 40:60 to 70, so as to easily secure mechanical properties such as strength and flame retardant properties, and to have sewing performance and a neat appearance with respect to the foaming layers 13b, 13 b'.

When the content of the polyester is more than the above range, combustibility, covering property and handleability are poor, and when the content of the polyester is less than the above range, mechanical properties are lowered, and thus, the polyester may be contained in the above range.

For example, the thickness of the coating layer formed on the backing layer 11 may be 1 to 10 μm or 2 to 5 μm. Wherein the thickness of the coating layer means a thickness including a coating solution impregnated into the backing layer 11. When the thickness of the coating layer is less than the above range, the peel strength of the backing layer 11 and the foaming layers 13b, 13b' may be reduced, and when it is more than the above range, the microhardness of the artificial leather may be increased, resulting in a reduction in touch feeling, and thus, it may be coated with the thickness within the above range.

The peel strength of the backing layer to the foamed layer after the coating solution is applied to the backing layer 11 may be 2.5 to 6kgf/30mm or 2.5 to 5.5kgf/30mm. When the amount is less than the above range, the backing layer 11 and the foam layers 13b and 13b' are easily peeled off, resulting in a reduction in the quality of the artificial leather, and when the amount is more than the above range, the microhardness is increased, resulting in a reduction in the touch, and therefore, it is preferable to maintain the peel strength in the above range.

In addition, the thickness of the backing layer 11 may be 0.4 to 0.7mm, and when it is less than the above range, mechanical strength may be lowered, and when it is more than the above range, it may be too thick, thereby requiring more material costs.

Step S3 of forming a preformed foam layer or foam layer and a surface layer

The step S3 may be a step of extrusion molding or calendaring molding the pre-foaming layer 13a or the foaming layer 13b and the skin layer 15.

The extrusion molding may be a T-die extrusion process using a T-die extruder after melting the pre-formed foam layer or the foam layer and the composition for producing a skin layer in the extruder, and the rolling molding may be a rolling process in which the pre-formed foam layer or the composition for producing a foam layer and a skin layer are kneaded in a stirrer and then passed through a rolling roll at 160 to 170 ℃.

Specifically, the pre-foaming layer 13a is formed into a sheet shape by extrusion molding or calender molding, and then foaming is performed in the foaming molding step S8 to form a foaming layer 13b', and the thickness of the pre-foaming layer 13a may be 0.2 to 0.35mm or 0.25 to 0.3mm.

Further, the foaming layer 13b is formed into a sheet shape by extrusion molding or calender molding, and then foamed by a heating furnace at 220 to 260 ℃, and the thickness thereof may be 0.4 to 0.8mm or 0.4 to 0.7mm, and when it is smaller than the above range, the cushioning effect is reduced, and when it is larger than the above range, it becomes too thick, thereby requiring more material cost.

More specifically, the pre-foaming layer 13a or the foaming layer 13b may be formed of a pre-foaming layer or a foaming layer manufacturing composition containing 60 to 120 parts by weight of a plasticizer and 5 to 15 parts by weight of a foaming agent with respect to 100 parts by weight of a polyvinyl chloride resin.

Specifically, the polyvinyl chloride resin contained in the pre-foaming layer 13a or the foaming layer 13b may be a linear (straight) polyvinyl chloride resin formed by suspension polymerization, which can secure both excellent cushioning and high elongation as well as excellent durability.

The polymerization degree of the polyvinyl chloride resin may be 900 to 1200 or 950 to 1150. When smaller than the above range, durability may be lowered, and when larger than the above range, hardness of the pre-foaming layer 13a or the foaming layer 13b may be increased, resulting in a reduction in cushioning feel, and thus, a polyvinyl chloride resin having a polymerization degree within the above range may be used.

In addition, the pre-foaming layer 13a or the foaming layer 13b of the present invention may further comprise a copolymer of vinyl chloride and vinyl acetate in an amount of 5 to 20 parts by weight or 5 to 15 parts by weight based on 100 parts by weight of the polyvinyl chloride resin to further impart adhesion to the backing layer 11 located at the lower portion, and in the above range, the peel strength with the backing layer 11 is excellent.

The vinyl acetate content in the copolymer of vinyl chloride and vinyl acetate may be 0.5 to 10% by weight or 1 to 5% by weight.

Alternatively, the pre-foaming layer 13a or the foaming layer 13b of the present invention may be a mixed resin which further includes one or more selected from Thermoplastic Polyurethane (TPU) resin, polyvinylidene chloride (PVDC) resin, polyvinylidene fluoride (PVDF) resin, chlorinated polyvinyl chloride (CPVC) resin, polyvinyl alcohol (PVA) resin, polyvinyl acetate (PVAc) resin, polyvinyl butyral (PVB) resin, polyethylene (PE) resin, and polypropylene (PP) resin, in addition to the polyvinyl chloride resin.

The plasticizer may be one or more selected from the group consisting of phthalate plasticizers, terephthalate plasticizers, and epoxy plasticizers.

The phthalate plasticizer may be a plasticizer having excellent compatibility with the polyvinyl chloride resin, for example, one or more selected from dibutyl phthalate, diethyl hexyl phthalate, diisononyl phthalate, diisodecyl phthalate, and butyl benzyl phthalate, and diisodecyl phthalate is preferably used as a plasticizer having low volatility.

The terephthalate-based plasticizer may use an environment-friendly plasticizer, for example, dioctyl terephthalate, but is not limited thereto.

The epoxy plasticizer may be obtained by epoxidizing the double bond of unsaturated fatty acid glyceride with hydrogen peroxide or peracetic acid, and for example, epoxidized soybean oil or epoxidized linseed oil may be used, but is not limited thereto.

60 to 120 parts by weight or 70 to 100 parts by weight of the plasticizer may be used based on 100 parts by weight of the polyvinyl chloride resin. When the amount is less than the above range, the workability and flexibility are lowered, and at the same time, the microhardness is increased, and when the amount is more than the above range, bleeding (bleeding) occurs in the plasticizer, and therefore, the plasticizer can be used in the above content range in which excellent flexibility can be achieved.

The foaming agent may be any fine bubbles having elasticity and thickness required to form the foaming layer 13b, and examples thereof include chemical foaming agents such as Azodicarbonamide (ADCA), p '-oxybis (benzenesulfonyl hydrazide) (p, p' -Oxybis (benzenesulfonyl hydrazide)), p-toluenesulfonyl hydrazide (p-toluenesulfonyl hydrazide), and sodium bicarbonate (Sodiumbicarbonate).

Based on 100 parts by weight of the polyvinyl chloride resin, 5 to 15 parts by weight or 5 to 10 parts by weight of the foaming agent may be used. When the amount is less than the above range, the softness and cushioning feel of the artificial leather are reduced, and when the amount is more than the above range, the foam layer 13b generates too many foam cells, and the surface physical properties and durability are lowered, so that the artificial leather can be used in the above range.

The foaming ratio of the foaming layer 13b may be 100 to 500% or 150 to 300%, and by having the foaming ratio in the above range, the uneven feeling, the cushioning feeling, and the soft surface touch feeling can be ensured, and when smaller than the above range, the microhardness of the artificial leather increases, and becomes hard, and when larger than the above range, that is, when excessively foaming, the durability and strength of the artificial leather decrease, resulting in a decrease in physical properties, and thus, the foaming ratio in the above range can be provided.

The foaming cells (cells) formed in the foaming layer 13b may be spherical foaming cells. The expression spherical foam unit is a representation of the shape relative to foam units having a distorted or sharp shape due to external pressure, and does not necessarily mean a geometrically perfect spherical shape, and is generally understood to cover the level that can be covered when each foam unit is said to be spherical. Therefore, in the present specification, the spherical foaming unit is not deformed by physical external force, and retains the spherical shape at the time of formation.

In addition, each 1mm of the side section or the horizontal section of the foaming layer 13b ² Can comprise 10 to 30 or 15 to 20 of said foaming units per unit area. When the amount is less than the above range, the softness and cushioning effect are reduced, and when the amount is more than the above range, the surface durability is reduced, and at the same time, physical properties such as the surface touch and cushioning effect are reduced, so that the number of foaming units in the above range can be included.

The number of foaming units was such that after cutting the artificial leather in the vertical or horizontal direction, each 1mm of the side or horizontal cross section at the foaming layer 13b was measured using an optical microscope ² The number of foam cells formed per unit area.

In addition, the average diameter of the foaming unit may be 120 to 250 μm or 135 to 200 μm. The average diameter means an average value of diameters that one foaming unit can have, more specifically, when the foaming unit is geometrically spherical, an average of diameters, and when it is other than geometrically spherical and distinguishes between a major axis and a minor axis, an average length of the major axis.

The average diameter of the foaming unit satisfies the above range and maintains a spherical shape, so that high softness and workability of the artificial leather can be ensured and excellent cushioning feeling can be exhibited.

The average diameter of the foaming unit was 1mm of the side or horizontal cross section of the foaming layer 13b measured using a Scale bar of an optical microscope after cutting the artificial leather in the vertical or horizontal direction ² An average diameter of the foam cells formed per unit area.

The specific gravity of the foaming layer 13b may be 0.7 to 0.9 or 0.7 to 0.8. When the specific gravity is less than the above range, durability is lowered, and when the specific gravity is greater than the above range, softness and cushioning feel are lowered.

Namely, inIn the foam layer 13b, the spherical foam cells are not structurally deformed by external pressure, and each 1mm of the side or horizontal cross section of the foam layer ² The artificial leather of the present invention has a remarkably improved cushioning feel and a soft surface touch because it includes 10 to 30 artificial leathers per unit area and has a specific gravity of 0.7 to 0.9.

The surface layer 15 is used to ensure surface smoothness and to express color, and may be formed of a composition for surface layer production containing 60 to 120 parts by weight of a plasticizer and a pigment based on 100 parts by weight of a polyvinyl chloride resin.

The polyvinyl chloride resin contained in the surface layer 15 has a higher polymerization degree than the polyvinyl chloride resin contained in the pre-foaming layer 13a or the foaming layer 13b, and thus the surface layer 15 can be prevented from being broken in the foaming step S8 or the embossing step S13 described later, which is preferable.

Specifically, the polyvinyl chloride resin included in the surface layer 15 may be a linear (linear) polyvinyl chloride resin manufactured by suspension polymerization.

The polymerization degree of the polyvinyl chloride resin contained in the surface layer 15 may be 1250 to 3000 or 1250 to 2000. When the amount is less than the above range, the surface layer 15 is at risk of breakage in the foam molding step S8 or the embossing step S13 described later, and when the amount is more than the above range, the surface touch and flexibility are reduced, and therefore, a polyvinyl chloride resin having a polymerization degree in the above range can be used.

The plasticizer contained in the composition for producing the surface layer 15 is the same as the plasticizer contained in the pre-foaming layer 13a or the foaming layer 13b, and thus a repetitive description thereof is omitted.

The composition for producing a pre-formed foam layer or a foam layer and a surface layer may further contain at least one selected from the group consisting of a heat stabilizer, a flame retardant and a filler, so long as the content thereof does not affect the physical properties, and the melt strength and physical properties are adjusted.

The thickness of the surface layer 15 may be 100 to 300 μm or 120 to 200 μm. When the amount is less than the above range, the surface smoothness and processability are lowered, and at the same time, the material cost is increased due to an increase in the amount of pigment exhibiting a color, and when the amount is more than the above range, the cushioning feel of the artificial leather is lowered, and at the same time, the artificial leather becomes excessively thick, resulting in a need for a large amount of material cost.

Backing layer laminating step S5

The step S5 may be a step of thermally laminating a surface-coated backing layer 11 on the bottom surface of the pre-foaming layer 13a or the foaming layer 13 b.

Step S7 of laminating surface layer

The step S7 may be a step of thermally laminating the skin layer 15 on top of the pre-foaming layer 13a or the foaming layer 13b on which the backing layer 11 is laminated.

Specifically, the reason why the surface layer 15 is laminated on the upper portion of the pre-foamed layer 13a or the foamed layer 13b on which the backing layer 11 is laminated after the backing layer 11 having one surface coated is thermally laminated on the bottom surface of the pre-foamed layer 13a or the foamed layer 13b is that the backing layer 11 has excellent mechanical strength, and therefore physical properties can be ensured at the time of performing the process. If the pre-formed foam layer 13a or the foam layer 13b and the surface layer 15 are laminated first, when the two layers 13a/13b, 15 are thermally laminated, air bubbles or curling such as layer bending may occur, and therefore, the backing layer 11 excellent in mechanical strength can be thermally laminated preferentially on the bottom surface of the pre-formed foam layer 13a or the foam layer 13 b.

In the step S7, when the pre-formed foam layer 13a is used, the foam molding step S8 of forming a semi-finished product in which the backing layer 11, the foam layer 13b', and the surface layer 15 are laminated may be further included by foaming the pre-formed foam layer 13a in a heating furnace at 220 to 230 ℃ after the step S7.

In this case, the foam layer 13b' has the same characteristics as the foam layer 13b described above, and thus a repetitive description thereof will be omitted.

Surface treatment layer Forming step S9

The step S9 is a step of applying an aqueous surface treatment agent to the upper part of the surface layer of the semi-finished product and drying the same to form the surface treatment layer 17, and may be applied as a single layer or as a plurality of layers of two or more layers.

The aqueous surface treatment agent may be a two-liquid aqueous surface treatment agent comprising 1 to 25 parts by weight of a curing agent, 1 to 25 parts by weight of an aqueous solvent, and 1 to 15 parts by weight of an organosilicon compound based on 100 parts by weight of a main agent.

The main agent may be a water-dispersed polycarbonate-based polyurethane resin, but is not limited thereto.

Each molecule of the curing agent may include one or more functional groups selected from an aziridine group, an isocyanate group, and a carbodiimide group.

The organosilicon compound may be a liquid polysiloxane in which polysiloxane is dispersed in water or a bead-like polysiloxane, and a liquid polysiloxane in which polysiloxane is dispersed in water with more excellent surface feel may be preferable.

The aqueous solvent may be water or an alcohol or a mixture of water and an alcohol.

When the aqueous surface treatment agent is applied as a single layer, the aqueous surface treatment agent can be applied, and when the aqueous surface treatment agent is applied as a multilayer, a composition other than an organosilicon compound can be applied as a substrate, and the aqueous surface treatment agent can be applied to the upper portion of the substrate.

The drying may be performed at 110 to 150 ℃ or 130 to 150 ℃ for 80 to 120 seconds. When the drying is performed at a temperature and for a time less than the above-mentioned temperature range, the aqueous solvent cannot evaporate and remain, which results in occurrence of whitening phenomenon on the surface of the artificial leather due to uncured state, and at the same time, the physical properties of the surface are lowered, and when the drying is performed at a temperature greater than the above-mentioned temperature range, the heat resistance is lowered, which results in discoloration, and thus the drying can be performed within the above-mentioned temperature and time range.

The whitening phenomenon is a defect in which white dots (dots) appear on the surface of the artificial leather after the aqueous surface treatment agent is applied.

The thickness of the surface treatment layer 17 formed may be 4 to 30 μm or 4 to 20 μm. By keeping the thickness of the surface treatment layer 17 within the above range, contamination resistance can be ensured while maintaining the softness of the artificial leather. When smaller than the above range, the thickness is too thin, resulting in a decrease in durability, and when larger than the above range, the need for an aqueous surface treatment agent increases, resulting in a need for more material costs, and thus, the thickness may be within the above range.

An infrared irradiation step S11

The step S11 may be a step of irradiating the surface of the surface layer 15 of the semi-finished product having the surface treatment layer 17 formed in the step S9 with infrared rays at 150 to 180 ℃ for 5 to 15 seconds or 10 to 15 seconds. When the infrared rays are irradiated at a temperature and for a time smaller than the above temperature, the surface layer 15 cannot be softened, so that the embossing cannot be formed well in the embossing step S13 described later, and when the infrared rays are irradiated at a temperature and for a time larger than the above temperature, the surface layer 15 is melted, and therefore the infrared rays can be irradiated in the above time.

For example, the process speed in the step S11 may be 10 to 20m/min or 12 to 15m/min, and specifically, when the process speed is 15m/min, the infrared ray may be irradiated for 14 seconds.

Embossing step S13

The step S13 is a step of forming the embossed patterns 19 by vacuum adsorption, and may be performed under a vacuum gauge pressure of 0.02 to 0.08MPa or 0.04 to 0.07 MPa. When the step is performed in a range smaller than the vacuum gauge pressure, it is difficult to form the embossed pattern 19, resulting in a reduction in cushioning, and when it is performed in a range larger than the above range, the surface treatment layer 17 is damaged, resulting in a reduction in surface physical properties, and thus, it is possible to perform in the vacuum gauge pressure range.

In addition, the step S13 may be performed at a temperature of 160 to 180℃or 170 to 180 ℃. When the process is performed in a temperature range less than the above range, it is difficult to sufficiently form the embossed patterns 19, and when the process is performed in a temperature range greater than the above range, the surface physical properties of the artificial leather become rough or torn due to the high temperature, and thus the process can be performed in the above temperature range.

In the above-described artificial leather manufacturing method of the present invention, the foam molding step S8, the surface treatment layer forming step S9, the infrared irradiation step S11, and the embossing step S13 may be configured in an inline manner.

In the artificial leather of the present invention, the surface treatment layer formed on the embossed valleys and peaks has a uniform thickness, and thus, has an excellent surface appearance.

The following preferred embodiments are set forth to aid in understanding the present invention, but it will be apparent to those skilled in the art that the following embodiments are merely illustrative of the present invention, and various changes and modifications are allowed within the scope and technical spirit of the present invention, and such changes and modifications should also fall within the scope of the appended claims.

Examples (example)

1. Manufacture of artificial leather

Example 1 ]

(1) Backing layer coating step S1

1) Preparation of coating solutions

A coating solution having a viscosity (Zahn cup, #3 cup) of 110 seconds at 25 ℃ was produced by completely stirring a coating composition containing 100 parts by weight of a plasticizer and 3 parts by weight of a curing agent with respect to 100 parts by weight of the mixed resin at normal temperature. Wherein the mixed resin consists of 75% by weight of a pasty vinyl chloride homopolymer and 25% by weight of a copolymer of vinyl chloride and vinyl acetate (the content of vinyl acetate is 6% by weight).

2) The coating solution prepared above was applied to one surface of a woven fabric in a thickness of 3 μm by gravure coating, and heated at 130℃to gel (gel) to prepare a backing layer having a thickness of 0.6 mm. Wherein the woven fabric comprises cotton and polyester at a ratio of 35:65.

(2) Prefabricated foam layer and surface layer Forming step S32-1) prefabricated foam layer 13a calendaring step

After kneading the foam layer-producing composition, the raw material in a stirred state was passed through a calender roll at 160 to 170 ℃ to produce a pre-foam layer 13 having a thickness of 0.3 mm. Wherein the composition for producing a foamed layer comprises 10 parts by weight of a copolymer of vinyl chloride and vinyl acetate (the content of vinyl acetate is 3% by weight), 85 parts by weight of a plasticizer, 6 parts by weight of a foaming agent, and 2 parts by weight of a heat stabilizer, based on 100 parts by weight of a linear polyvinyl chloride resin having a polymerization degree of 1000.

2-2) step of calendaring the surface layer 15

After kneading the composition for producing a skin layer, the raw material in a stirred state was passed through a calender roll at 160 to 170 ℃ to produce a skin layer having a thickness of 150 μm. Wherein the composition for producing a surface layer comprises 95 parts by weight of a plasticizer, 2 parts by weight of a pigment, and 2 parts by weight of a heat stabilizer, based on 100 parts by weight of linear polyvinyl chloride having a polymerization degree of 1300.

(3) Backing layer laminating step S5

Next, a surface-coated backing layer 11 is thermally laminated on the bottom surface of the pre-foaming layer 13 a.

(4) Step S7 of laminating surface layer

A skin layer 15 is thermally laminated on the upper portion of the pre-foaming layer 13a on which the backing layer 11 is laminated.

(5) Foaming step S8

A semi-finished product formed by laminating the backing layer 11, the pre-foaming layer 13a, and the surface layer 15 is passed through a heating furnace to foam the pre-foaming layer 13a, thereby manufacturing a semi-finished product formed by laminating the backing layer 11, the foaming layer 13b', and the surface layer 15.

(6) Surface treatment layer Forming step S9

At a rate of 40 to 50g/m on the surface layer 15 ² After gravure coating of the aqueous surface treatment agent, drying was performed at 140 ℃ to evaporate the aqueous solvent, thereby forming the surface treatment layer 17 having a thickness of 15 μm. Wherein the aqueous surface treatment agent comprises 5 parts by weight of a curing agent based on 100 parts by weight of a polycarbonate-based polyurethane resin 20 parts by weight of an aqueous solvent and 5 parts by weight of an organosilicon compound.

(7) An infrared irradiation step S11 and an embossing step S13

Then, the surface of the semi-finished product formed of the backing layer 11, the foaming layer 13b', the surface layer 15 and the surface treatment layer 17 from bottom to top was irradiated with infrared rays at 150 to 180 ℃ for 14 seconds to heat it to about 170 ℃, and then embossed patterns 19 were formed by adsorption on the surfaces of the surface layer 15 and the surface treatment layer 17 under a vacuum gauge pressure of 0.06Mpa, thereby completing the production of the artificial leather of the present invention.

< example 2 to example 10>

The artificial leather manufactured in the above example 1 was cut in an arbitrary direction to prepare an evaluation sample for measuring the gloss difference between the valleys 19a and the peaks 19b of the embossed patterns 19.

Comparative example 1 ]

An artificial leather was manufactured in the same manner as in example 1, except that after the foam molding step S8, an embossing was performed on the surface of the skin layer 15 using an embossing roller having an embossing pattern under a pressure of 4Mpa to form an embossing, and the surface of the skin layer 15 on which the embossing was formed was coated with the same amount of aqueous surface treating agent as in example 1 to form a surface treated layer.

Comparative example 2 to comparative example 10

The artificial leather manufactured in the above comparative example 1 was cut at any different position to prepare an evaluation sample for measuring the difference in gloss between the valleys 19a and the peaks 19b of the embossed patterns 19.

2. Thickness measurement of surface treated layer of artificial leather

The artificial leathers of example 1 and comparative example 1 manufactured as above were cut in the vertical direction, and then the thickness of the surface-treated layer formed on the embossed valleys and peaks was measured by a high-magnification optical microscope, and the results thereof are shown in table 1 below.

TABLE 1

As shown in table 1 above, it was confirmed that in example 1, which is an artificial leather of the present invention, the thickness of the surface-treated layer formed on the embossed valleys and peaks was 15 μm, and was very uniform, and the ratio of the thickness of the surface-treated layer formed on the embossed peaks to the thickness of the surface-treated layer formed on the embossed valleys was 1, satisfying a specific range of 0.7 to 1, and therefore, the difference in gloss of the surface-treated layer was small, and the surface appearance was excellent, whereas in the artificial leather of comparative example 1, the difference between the thickness of the surface-treated layer formed on the embossed valleys and the thickness of the surface-treated layer formed on the peaks was 5 μm, the difference was large, the ratio of the thickness of the surface-treated layer formed on the embossed peaks to the thickness of the surface-treated layer formed on the embossed valleys was 0.6, and the difference in gloss of the surface-treated layer formed on the valleys and peaks was large, and therefore, the surface appearance was uneven.

3. Physical property measurement of artificial leather

(1) The surface appearance of the difference in gloss between the valleys 19a and the peaks 19b of the embossments 19 of the artificial leather sample surfaces according to examples 2 to 10 and comparative examples 2 to 10 manufactured above was measured and is shown in table 2 below.

The gloss difference was defined as a gloss difference when the number of people considering the gloss difference of the artificial leather sample was 5 or more, and was noted as X (poor appearance), and as no gloss difference when the number of people considering the gloss difference was less than 5, and was noted as o (excellent appearance).

TABLE 2

As shown in table 2 above, it can be confirmed that the artificial leathers of examples 2 to 10 of the present invention have no or very little gloss difference compared to the conventional artificial leathers of comparative examples 2 to 10 coated with the surface treatment agent after embossing by roll forming, the gloss difference between the valleys and peaks is not sensed by most of the evaluators, and the surface appearance of the artificial leathers of the present invention is excellent compared to the artificial leathers of the comparative examples.

(2) Microhardness, peel strength, softness (Softness), touch feeling, and compactibility of the artificial leathers of example 1 and comparative example 1 manufactured as described above were measured and are shown in table 3 below.

Microhardness

Microhardness is the maximum measured after a indenter was brought into contact with the artificial leather at an indentation speed of 1mm/s in a peak hold mode using a microhardness tester (Asker Micro Durometer company, model: MD-1 CAPA), i.e., when the load holding time of the indenter was 1 s.

Peel strength

The artificial leather produced in the above-mentioned item 1 was produced into test pieces having a width of 30mm and a length of 150mm, 5 test pieces were collected in the lateral direction and the longitudinal direction, and after immersing the air cell side in a solvent such as Methyl Ethyl Ketone (MEK), the skin (foam layer) and the air cell (backing layer) were forcibly peeled in parallel with the short side by a length of 50mm while avoiding the application of stress to the skin (foam layer).

After peeling, the test piece was left in the room for 2 hours or more, and after the solvent was sufficiently volatilized, the peeled skin (foam layer) and air bubbles (backing layer) were fixed to the jaws of the tensile tester, respectively, and then the average value of the maximum value of the load when peeling at 200mm/min was determined.

The test results were averaged over 5 samples.

Softness-softness

Softness (Softness) is measured by a Softness measuring device (SDL Atlas, ST 300D) at a temperature of 23+ -2deg.C and a relative humidity of 50+ -5%, by pressing with an ST300D device after preparing 5 artificial leather samples having pi value of 100mm, and reading the value of scale movement within 15 seconds.

-tactile sensation

The interior panelists of the artificial leather directly touched with the hands to evaluate the degree of relative softness.

(verysoft, good, soft, [ delta ] flat touch)

-degree of compaction

The compactness is that 5 artificial leather samples with the width of 250mm and the length of 200mm are respectively taken in the transverse direction and the longitudinal direction, and are placed on a horizontal table in a manner that the short sides are aligned with a SCALE base line (A).

Next, the specimen is pressed by a pressing plate of the same size as the specimen and slid in the direction of the inclined surface at a speed of about 10 mm/sec, and when one end of the specimen is in contact with the inclined surface, the position (B) of the other end is read out by a SCALE (SCALE).

The degree of compaction is shown by the distance of movement (scale of point B) (mm), and 5 surfaces and backs were measured in both the longitudinal and transverse directions, and the average value thereof was taken.

TABLE 3 Table 3

	Example 1	Comparative example 1
			Microhardness	54	66
Peel strength [ kgf/30mm ]]	3	3
			Softness (Softness)	3.8	3.3
Tactile sensation	◎	△
			Compactness (mm)	52	76

As shown in table 3, it was confirmed that the artificial leather of example 1 of the present invention has lower microhardness, higher softness and soft touch than the artificial leather of comparative example 1 in which embossing was performed by roll-type instead of vacuum adsorption, and thus, the surface touch was excellent. In addition, it was confirmed that the artificial leather of example 1 of the present invention was low in compactness and high in softness as compared with the artificial leather of comparative example 1.

4. Size, number, shape and measurement of foaming units of foaming layer of artificial leather

When the artificial leathers of example 1 and comparative example 1 manufactured as described above were cut in the vertical direction, the size (diameter), number and shape of the foaming units included in the side cross section of the foaming layer were measured, and the result values thereof are shown in table 4 below.

The foaming unit size (average diameter) is 1mm of the side section formed on the foaming layer 13b' using a Scale bar of an optical microscope after cutting the artificial leather in the vertical direction ² The average diameter of the foaming units per unit area was measured.

The number of foaming units is 1mm of the side section formed on the foaming layer 13b' after cutting the artificial leather in the vertical direction using an optical microscope ² The number of foam cells per unit area is measured.

TABLE 4 Table 4

	Example 1	Comparative example 1
			Foaming cell size [ mu ] m]	135～200	100～400
Number of foaming units [ number/mm ] ² ]	15～20	5～10
			Foaming unit shape	Spherical shape	Non-uniformity of
Thickness of foaming layer (mm)	0.5	0.3

As shown in Table 4, it was confirmed that the artificial leather of example 1 of the present invention was embossed by calender molding and vacuum molding, after the embossing molding, the foam cells in the foam layer remained in a spherical shape, the size (average diameter) of the foam cells was 135 to 200. Mu.m, and the number of foam cells in the side section of the foam layer was 15 to 20 per mm ² Thus, a lightweight and excellent cushioning effect, high flexibility, excellent touch feeling, and the like can be achieved. In contrast, the artificial leather of comparative example 1 was embossed by roll forming, the shape of the foaming unit was in an irregular shape such as being elongated or twisted, the size of the foaming unit was small and the number was small, the thickness of the foaming layer was thin, and the cushioning feel, softness, touch feel and the like were inferior to those of the artificial leather of example 1.

5. Embossing transfer efficiency

On the other hand, as a result of measuring the transfer efficiency of the embossing of the artificial leather of example 1 and comparative example 1, the artificial leather of comparative example 1 was embossed with an embossing apparatus of a roll press system, and the transfer efficiency of the embossing was 80 to 90%, whereas the artificial leather of example 1 of the present invention was embossed with an embossing apparatus of a vacuum, and therefore, the transfer efficiency of the embossing was nearly 100%.

Claims

1. An artificial leather, which is characterized in that,

the ratio of the thickness of the surface treatment layer formed on the peaks of the embossment to the thickness of the surface treatment layer formed on the valleys of the embossment is 0.7 to 1,

wherein the artificial leather comprises a backing layer, a foaming layer, a surface layer and a surface treatment layer from bottom to top, and comprises embossments formed on the upper parts of the surface layer and the surface treatment layer,

The foaming layer is formed by a composition for producing the foaming layer, the composition for producing the foaming layer comprises 60-120 parts by weight of plasticizing agent and 5-15 parts by weight of foaming agent based on 100 parts by weight of polyvinyl chloride resin, the polyvinyl chloride resin contained in the foaming layer is linear polyvinyl chloride resin with the polymerization degree of 950-1150,

the surface layer is formed from a composition for producing a surface layer, the composition for producing a surface layer comprising 60 to 120 parts by weight of a plasticizer and a pigment based on 100 parts by weight of a polyvinyl chloride resin, the polyvinyl chloride resin contained in the surface layer having a polymerization degree of 1250 to 2000,

the surface treatment layer is formed by coating an aqueous surface treatment agent comprising 1 to 25 parts by weight of a curing agent, 1 to 25 parts by weight of an aqueous solvent and 1 to 15 parts by weight of an organosilicon compound based on 100 parts by weight of a polycarbonate-based polyurethane resin on the upper part of the surface layer and drying at 110 to 150 ℃ for 80 to 120 seconds,

the embossing is formed by vacuum adsorption molding on the upper parts of the surface layer and the surface treatment layer, wherein the surface layer and the surface treatment layer are heated by irradiation of infrared rays at 150 to 180 ℃ for 5 to 15 seconds before the embossing is formed,

The microhardness of the artificial leather is 45 to 59, which is the maximum value measured after the indenter is brought into contact with the artificial leather at an indentation speed of 1mm/s in a peak hold mode using a microhardness meter, that is, when the load holding time of the indenter is 1 s.

2. The artificial leather according to claim 1, wherein,

the difference in thickness of the surface treatment layer formed between the peaks and the valleys of the embossment is less than 5 μm.

3. The artificial leather according to claim 1, wherein,

the area where the ratio of the thickness of the surface treatment layer formed on the peaks of the embossment to the thickness of the surface treatment layer formed on the valleys of the embossment is 0.7 to 1 is 80% or more of the entire surface of the artificial leather.

4. A method for manufacturing an artificial leather according to any one of claims 1 to 3, comprising:

a backing layer coating step (S1) of coating a coating solution on one surface of a backing layer, wherein the backing layer is woven cloth or non-woven cloth;

a step (S3) of forming a pre-formed foam layer or a foam layer and a surface layer, respectively forming the pre-formed foam layer or the foam layer and the surface layer;

a backing layer laminating step (S5) of laminating the backing layer coated on one surface on the bottom surface of the prefabricated foaming layer or the foaming layer;

A surface layer lamination step (S7) in which the surface layer is laminated on top of a pre-formed foam layer or a foam layer on which the backing layer is formed;

a surface treatment layer forming step (S9) of applying an aqueous surface treatment agent to the upper part of the surface layer and drying the surface layer at 110 to 150 ℃ for 80 to 120 seconds to form a surface treatment layer, wherein the aqueous surface treatment agent comprises 1 to 25 parts by weight of a curing agent, 1 to 25 parts by weight of an aqueous solvent and 1 to 15 parts by weight of an organosilicon compound based on 100 parts by weight of a polycarbonate-based polyurethane resin;

an infrared irradiation step (S11) of irradiating an upper portion of the surface treatment layer with infrared rays, wherein the infrared rays are irradiated at 150-180 ℃ for 5-15 seconds;

an embossing step (S13) of forming embossing by adsorption on the upper parts of the surface layer and the surface treatment layer heated by irradiation of the infrared rays by vacuum,

wherein the pre-foaming layer or the foaming layer is formed by a composition for manufacturing the pre-foaming layer or the foaming layer, the composition for manufacturing the pre-foaming layer or the foaming layer comprises 60 to 120 weight parts of plasticizing agent and 5 to 15 weight parts of foaming agent based on 100 weight parts of polyvinyl chloride resin, the polyvinyl chloride resin contained in the pre-foaming layer or the foaming layer is linear polyvinyl chloride resin with the polymerization degree of 950 to 1150,

5. The method for manufacturing artificial leather according to claim 4, wherein,

the coating solution of the step (S1) is formed by stirring 70 to 130 parts by weight of a plasticizer and 0.5 to 10 parts by weight of a curing agent at normal temperature with respect to 100 parts by weight of a polyvinyl chloride resin.

6. The method for manufacturing artificial leather according to claim 5, wherein,

the polyvinyl chloride resin is a mixed resin composed of 60-90 wt% of homopolymer of vinyl chloride and 10-40 wt% of copolymer of vinyl chloride and vinyl acetate.

7. The method for manufacturing artificial leather according to claim 4, wherein,

The viscosity of the coating solution of step (S1) was measured as Cai Enbei and was 80 to 140 seconds at 25 ℃.

8. The method for manufacturing artificial leather according to claim 4, wherein,

the peel strength of the backing layer and the foaming layer is 2.5-6 kgf/30mm.

9. The method for manufacturing artificial leather according to claim 4, wherein,

the step (S3) is a step of forming the pre-formed foam layer or the foam layer and the surface layer by extrusion molding or calendaring molding.

10. The method for manufacturing artificial leather according to claim 4, wherein,

the foaming rate of the foaming layer is 100-500%.

11. The method for manufacturing artificial leather according to claim 4, wherein,

the foaming units formed on the foaming layer are spherical foaming units with average diameter of 120-250 μm, and each 1mm of side section or horizontal section of the foaming layer ² Comprises 10 to 30 of said foaming units per unit area.

12. The method for manufacturing artificial leather according to claim 4, wherein,

in the step (S3), a pre-foaming layer (13 a) and a surface layer (15) are formed, respectively, and further comprising a foam molding step (S8) of foaming the pre-foaming layer (13 a) to form a foaming layer (13 b') after the step (S7).

13. The method for manufacturing artificial leather according to claim 4, wherein,

the step (S13) is a step of forming embossing by vacuum adsorption, and is performed under a vacuum gauge pressure of 0.02-0.08 Mpa and a temperature of 160-180 ℃.